Question

The reaction of 2-ethyl-1-pentene with Br₂, with H₂ + Pd/C, or with R₂BH/THF followed by aqueous HO^- + H₂O₂ leads to a racemic mixture. Explain why a racemic mixture is obtained in each case.

Short answer

Each of the reaction forms a compound with one asymmetric centre from a compound with no asymmetric centre so it will form racemic mixture.

Step-by-step solution

Some definitions

What is racemic mixture-

When two enantiomers are formed in one reaction so the product will form racemic mixture.

What is markoniv’s addition

In thispositive charge will go to that double bonded carbon which has more no of hydrogens attached and negative charge will go towards that carbon which has less number of hydrogens attached.

Final answer

In first reaction bromination will take place. Both double bonded carbon atom will attach with one bromine atom.

In second reaction reduction takes place. Addition of H₂takes place.

In third reaction anti markoniv’s addition obeys.

Each of the reaction forms a compound with one asymmetric centre from a compound with no asymmetric centre so it will form racemic mixture.